I was just thinking that if my husband was to ever have an affair I hope he would use a condom or some other contraceptive. Wouldn’t it be worse to not use a condom, since a neglect to do so could lead to disease or a pregnancy that could cause both families to break up? I know that having affairs is wrong, but if someone was to have an affair, wouldn’t using a condom be the lesser of the evils?
What you have basically outlined here is an extension on the argument of why teens should use condoms. The argument goes something like this: We want teens to remain chaste and save sex for marriage. Realistically speaking though, we know that they probably won’t do so and will probably have sex anyway, so let’s give them condoms for “protection.” In your hypothetical, you’ve expanded the argument to say that a spouse should stay faithful but, if he won’t, let’s hope that he’ll at least use a condom.
Let’s look at the problems with this argument:
First: One of the traditional safeguards against adultery has been the fear of pregnancy or disease. If it becomes licit for a married man to use contraception while cheating on his wife, he is left with little to prevent him from doing so. Pope Paul VI commented in Humanae Vitae on this point, saying:
Responsible men can become more deeply convinced of the truth of the doctrine laid down by the Church on this issue if they reflect on the consequences of methods and plans for artificial birth control. Let them first consider how easily this course of action could open wide the way for marital infidelity and a general lowering of moral standards. Not much experience is needed to be fully aware of human weakness and to understand that human beings – and especially the young, who are so exposed to temptation – need incentives to keep the moral law, and it is an evil thing to make it easy for them to break that law (HV 17).
Second: Contraception is not foolproof. Condoms are almost useless in defense against one of the deadliest and most common of the sexually-transmitted diseases: human papillomavirus (HPV). Saying that contraception is licit when used by a cheating spouse would be to lull the couple into a false sense of security.
Third: Let’s say that the cheating spouse was lulled into this false sense of security and believed himself impervious to STDs and pregnancy because he was using a condom. In the case of an STD, if his wife or children end up with an STD because of him, he may not believe it his fault and accuse his innocent wife of cheating on him! In the case of pregnancy, he may accuse his partner in infidelity of infidelity in their relationship and refuse to take responsibility for an innocent child who will then be at risk for abortion, at worst, or a fatherless childhood, at best.
In short, a cheating spouse who uses contraception is merely compounding his sin; he is not mitigating it.